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Mortgage servicing rights - Changes in Mortgage Servicing Rights (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Servicing Asset at Fair Value, Amount [Roll Forward] |  |  |
Carrying value at beginning of period | $ 75,521,000 | $ 88,829,000 | $ 76,107,000
Capitalization | 47,025,000 | 42,151,000 | 54,913,000
Mortgage servicing rights acquired from Franklin, at fair value | 5,111,000 | 0 |
Sales | 0 | (29,160,000) | (39,428,000)
Change in fair value: |  |  |
Due to pay-offs/pay-downs | (27,834,000) | (16,350,000) | (11,062,000)
Due to change in valuation inputs or assumptions | (19,826,000) | (9,949,000) | 8,299,000
Carrying value at end of period | $ 79,997,000 | $ 75,521,000 | $ 88,829,000

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- Definition Servicing asset at fair value, changes in fair value due to pay-offs or pay-downs. + References No definition available. + Details
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- Definition Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 4 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122492-111745 Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 45 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745 + Details
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- Definition Amount of additions from purchases, assumption or transfer to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 4 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746 + Details
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- Definition Amount conveyed to unrelated parties of contract to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 4 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122739-111746 + Details
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- Definition Amount of increase (decrease) in fair value from changes in the inputs, assumptions, or model used to calculate the fair value of the contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a)(4)(i) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746 + Details
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